Limaco ULM-3D Series, Operating And Installation Manual

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After connecting the interface converter to USB, install the device driver, if neces-
sary. Right-click "My Computer" shortcut and select "Properties" from the context
menu. In "System Properties" window that opens, in "Hardware" tab, click "Device
Manager" button (the procedure for Win XP). In the hardware list, open "COM and
LPT Ports" section. Find the COM-port corresponding to the connected device,
double-click "Properties" window of the selected port, and make sure that the de-
vice is working properly.
RS485 information line is arranged using a twisted pair cable with a wave resistance
of 120 Ohm. The external cable insulation shall provide sufficient mechanical and
electrical strength for the customer's process and climatic conditions. The total
length of line can reach several kilometers.
Fig. 6.4 Conventional method of RS-485 line laying
The diagram of the conventional method of line laying that meets the general re-
quirements of RS-485 standard, designed for high-speed data transmission in man-
made noise is shown in Fig. 6.4. If the line is long, install 120 Ohm matching resis-
tors at the ends of the line between "A" and "B" wires. For this purpose, a switch
that connects this resistor to the line, designated as R
A-B
on the nameplate, is pro-
vided in the level transmitter. Note that this resistor is also installed inside some in-
terface converters. If the line length is more than 800 m or the number of devices
on the line is more than 32 pieces, use standard repeaters for RS-485, for example,
ADAM-4510.
Do not connect devices with a data exchange protocol other than Modbus RTU to
the information line of level transmitter.
The same information line shall not have sensors with the same Modbus addresses.
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ATTENTION
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ATTENTION
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